Search

With the development of multi electric/all electric aircraft, the degree of aircraft secondary energy electrification is becoming higher and higher. As the core component of the electrical system, the motor presents the trend of small volume and high-power density. The heat dissipation problem of compact motor is becoming more and more serious. At present, the self-driven fan cooling system is widely used in aircraft motors. In this paper, the axial fan cooling system of an aero generator is taken as the research object, and the changes of fan flow field and aerodynamic characteristics in the fan motor coupling model of the isolated fan and the installed motor are analyzed by using three-dimensional computational fluid simulation. At the same time, the influence of the change of the axial distance between the fan and the motor on the aerodynamic performance is also studied. The analysis of the simulation results shows that the close coupling between the motor and the fan components greatly affects the flow structure in the fan, resulting in the distortion potential effect on the fan outlet section. The fan flow field appears the blade root reflux, the channel vortex in the blade and the expansion of the corner separation area. With the increase of the axial distance between the motor and the fan, the influence of the motor on the flow in the fan gradually approaches the flow blocking effect.

In hover, the lip of a lift fan plays a crucial role, contributing to nearly half of the lift for the VTOL aircraft power plant. Thus, investigating the geometric parameters that influence lip performance is of significant importance. In this study, four types of lift fan lips were designed, tailored to meet specific application requirements. Numerical analysis, validated through experimental data, was employed to examine the flow field and the geometric factors that lead to variations in lip performance. Based on the findings, the relationship between lip geometric parameters and aerodynamic performance was thoroughly investigated and confirmed. The results demonstrate that, at a rotational speed of 10 000 r/min, the non-dimensional lift and non-dimensional mass flow of the lemniscate lip exhibit improvements of 33% and 9.5%, respectively, compared to lips designed based on NACA65. Among the various lip configurations, it is found that the performance parameters of the lip are optimal when the slope of the inner surface equaled twice the slope of the lemniscate. On the other hand, when the slope deviated from this optimal value, whether greater or lesser, a reduction in lip performance was observed. Specifically, at a rotational speed of 10 000 r/min, the lip designed based on a lemniscate slope could increase the total lift of the lift fan by 5.6% when compared to the lemniscate lip.

The cost of obtaining a large amount of flow field information by traditional experiment or CFD is unacceptable,so it is of significance to develop faster forecasting calculation methods.Proper orthogonal decomposition(POD)is used to extract the dominant mode of the tandem flow field.Radial basis function network(RBFN)is used to respond to the coefficients of the POD basis functions to realize the construction of the reduced-order prediction model of the flow field.Then the adaptive sampling method is developed for the reduced order model.The prediction model is verified by the unsteady flow field data of a cascade.It is concluded that the hybrid method can be utilized to accurately predict the aerodynamics parameters and flow field of tandem cascade.Compared with static sampling,the number of samples required for adaptive sampling to achieve the same reconstruction accuracy is reduced by about 25%.

The highly-efficient and unsteady aerodynamic simulation of turbomachinery is urgently required. The panel-vortex particle method is coupled with a far free field sound model established with the Lowson method and aims to fast predict aerodynamic and acoustic properties. The aerodynamic results show that, compared with the aerodynamic results acquired with the finite volume method, the use of the panel-vortex particle method may obtain appropriate pressure distribution and velocity distribution in the downstream region of a propeller and that the overall thrust prediction is accurate enough. The vortex distribution features show that the panel-vortex particle method has less numerical diffusion. Therefore, the velocity gradient is more accurate near the wake vortex. Compared with the sound pressure level acquired with the finite volume method, the sound pressure level simulated with the panel-vortex particle method has the same directivity pattern. The relative error of sound pressure in the 60° forward direction is 5% under 1BPF(blade passing frequency), which satisfies acoustic analysis requirements. As for time consumption, the use of the panel-vortex particle method consumes 10% of time when the finite volume method is used, proving that the panel-vortex particle method coupled with the Lowson method can satisfy the design and application needs of unsteady aerodynamic and aeroacoustic noise of a distributed electric propulsion system.